Glass containers may be coated with one or more coating compositions during manufacture to impart scratch resistance, lubricity, and/or decoration to the glass containers. For example, U.S. Pat. No. 3,522,075 discloses a process for coating a glass container with an organopolysiloxane coating. The glass container is first coated or primed with a metal oxide layer after it leaves a glass-forming machine, but before it is passed through an annealing lehr. Upon exiting the annealing lehr, an organopolysiloxane resin-based coating composition is applied to the glass container over the metal oxide layer to form the organopolysiloxane coating.
A general object, in accordance with one aspect of the present disclosure, is to provide a process for strengthening a glass container by applying an aminofunctional silane coating composition to an exterior surface of the glass container, and then curing the coating composition to form a siloxane coating on the exterior surface of the glass container. The siloxane coating can fill-in or “heal” any commercial variations or anomalies on the exterior surface of the glass container, which can improve the mechanical strength of the glass container.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
In accordance with one aspect of the disclosure, there is provided a method of forming a siloxane coating on a glass container by applying a silane coating composition to an exterior surface of the glass container, and then curing the silane coating composition to form the siloxane coating on the exterior surface of the glass container. The silane coating composition is preferably an aqueous solution that includes, and most preferably consists essentially of, an aminofunctional silane and water.
In accordance with another aspect of the disclosure, there is provided a method of forming a siloxane coating on a glass container by: (a) applying a first silane coating composition to a surface of the glass container; (b) curing the first silane coating composition to form a first siloxane layer on the surface of the glass container; (c) applying a second silane coating composition to the surface of the glass container over the first siloxane layer; and then (d) curing the second silane coating composition to form a second siloxane layer over the first siloxane layer on the surface of the glass container. The first silane coating composition of step (a) preferably includes, and most preferably consists essentially of, an aminofunctional silane and water.
In accordance with yet another aspect of the disclosure, there is provided a method of manufacturing a soda-lime-silica glass container by: (a) forming the glass container, (b) forming a hot-end coating on an exterior surface of the glass container; (c) annealing the glass container; (d) forming a siloxane coating on the glass container over the hot-end coating; and then (e) forming a cold-end coating on the glass container over the siloxane coating. The siloxane coating is formed on the glass container by applying a silane coating composition to the glass container over the hot-end coating and then curing the silane coating composition. The silane coating composition is preferably an aqueous solution that includes, and most preferably consists essentially of, an aminofunctional silane and water.